1. Field of the Invention
The present invention relates to a planar pulse motor, an exposure apparatus, and a device manufacturing method.
2. Description of the Related Art
FIGS. 6 and 7 illustrate the structure of a conventional planar pulse motor. A mover 60 can move in X and Y directions while floating in air, for example, 20 micrometers above a stator 1. As illustrated in FIG. 7, the stator 1 of a conventional planar pulse motor is configured from rows on which raised portions 2 and recessed portions 3 are arranged alternately in the Y direction, and rows on which only recessed portions 3 and no raised portions 2, are arranged in the Y direction. The two kinds of rows are provided alternately in the X direction. The raised portions 2 are regions which allow magnetic flux to pass through in both the X and Y directions. The recessed portions 3 are regions which do not allow magnetic flux to pass through in either the X or the Y direction.
In a conventional planar pulse motor, the dimension ratio between raised portions 2 and recessed portions 3 of the stator 1 is usually about 1 to 1. Therefore, the area ratio of the raised portions 2 on the surface of the stator 1 is about 1/4. Thus, in a conventional planar pulse motor, a pass area through which the magnetic flux flows into the raised portions 2 of the stator 1 from the tooth tips of the mover 60 is about ½ that of a single axis linear pulse motor, so that the utilization efficiency of the magnetic flux is low. Therefore, it is difficult to obtain a high thrust in a conventional planar pulse motor.